U.S. patent application number 12/582455 was filed with the patent office on 2010-02-18 for spin bowl compatible polyamic acids/imides as wet developable polymer binders for anti-reflective coatings.
Invention is credited to Robert Christian Cox, Charles J. Neef.
Application Number | 20100040988 12/582455 |
Document ID | / |
Family ID | 29999172 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100040988 |
Kind Code |
A1 |
Cox; Robert Christian ; et
al. |
February 18, 2010 |
SPIN BOWL COMPATIBLE POLYAMIC ACIDS/IMIDES AS WET DEVELOPABLE
POLYMER BINDERS FOR ANTI-REFLECTIVE COATINGS
Abstract
Anti-reflective compositions and methods of using these
compositions to form circuits are provided. The compositions
comprise a polymer dissolved or dispersed in a solvent system. In a
preferred embodiment, the polymers of the composition include
recurring monomers having the formulas ##STR00001## where: (1) each
R is individually selected from the group consisting of hydrogen,
--OH, aliphatics, and phenyls; and (2) L is selected from the group
consisting of --SO.sub.2-- and --CR'.sub.2--, where each R' is
individually selected from the group consisting of hydrogen,
aliphatics, phenyls, and --CX.sub.3, where each X is individually
selected from the group consisting of the halogens. The resulting
compositions are spin bowl compatible (i.e., they do not crosslink
prior to the bake stages of the microlithographic processes or
during storage at room temperature), are wet developable, and have
superior optical properties.
Inventors: |
Cox; Robert Christian; (St.
James, MO) ; Neef; Charles J.; (Rolla, MO) |
Correspondence
Address: |
HOVEY WILLIAMS LLP
10801 Mastin Blvd., Suite 1000
Overland Park
KS
66210
US
|
Family ID: |
29999172 |
Appl. No.: |
12/582455 |
Filed: |
October 20, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11264858 |
Nov 2, 2005 |
7608380 |
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12582455 |
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10842997 |
May 11, 2004 |
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11264858 |
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10180624 |
Jun 25, 2002 |
7261997 |
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10842997 |
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60349569 |
Jan 17, 2002 |
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Current U.S.
Class: |
430/325 ;
430/322 |
Current CPC
Class: |
C08G 73/10 20130101;
C08G 73/1025 20130101; C09D 179/08 20130101; C08G 73/1039 20130101;
G03F 7/091 20130101; Y10S 430/106 20130101; G02B 1/111 20130101;
G03F 7/038 20130101; C08G 73/1064 20130101; Y10S 430/151
20130101 |
Class at
Publication: |
430/325 ;
430/322 |
International
Class: |
G03F 7/20 20060101
G03F007/20 |
Claims
1. A method of using a composition in photolithographic processes,
said method comprising the steps of: applying a quantity of a
composition to a substrate to form a layer thereon, said
composition comprising a polymer dissolved or dispersed in a
solvent system, said polymer comprising recurring monomers having
the formulas ##STR00013## where each of ##STR00014## individually
represent an aryl or aliphatic group; and exposing at least a
portion of said layer to DUV light.
2. The method of claim 1, further including the step of baking said
layer, after said applying step, at a temperature of from about
100-250.degree. C. to yield a cured layer.
3. The method of claim 2, further including the step of applying a
photoresist to said cured layer prior to said exposing step.
4. The method of claim 3, wherein said exposing step comprises
exposing said photoresist to DUV light.
5. The method of claim 4, furthering including the steps of
developing said photoresist after said exposing step,
6. The method of claim 5, wherein said developing step results in
the removal of said cured layer from areas adjacent said exposed
photoresist.
7. A method of using a composition in photolithographic processes,
said method comprising the steps of: applying a quantity of a
composition to a substrate to form a layer thereon, said
composition comprising a polyamic acid dissolved or dispersed in a
solvent system; and exposing at least a portion of said layer to
DUV light.
8. The method of claim 7, wherein said polyamic acid is a copolymer
of a compound having the formula ##STR00015## where ##STR00016##
represents an aryl or aliphatic group, and a compound having the
formula ##STR00017## where ##STR00018## represents an aryl or
aliphatic group.
9. The method of claim 8, wherein (I) is selected from the group
consisting of ##STR00019##
10. The method of claim 8, wherein (II) is selected from the group
consisting of ##STR00020##
11. The method of claim 7, said polyamic acid comprising recurring
monomers having the formulas ##STR00021## where each of
##STR00022## individually represent an aryl or aliphatic group.
12. The method of claim 7, further including the step or baking
said layer, after said applying step, at a temperature of from
about 100-250.degree. C. to yield a cured layer.
13. The method of claim 12, further including the step of applying
a photoresist to said cured layer prior to said exposing step.
14. The method of claim 13, wherein said exposing step comprises
exposing said photoresist to DUV light.
15. The method of claim 14, furthering including the steps of
developing said photoresist after said exposing step.
16. The method of claim 15, wherein said developing step results in
the removal of said cured layer from areas adjacent said exposed
photoresist.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/264,858, filed Nov. 2, 2005, incorporated
by reference herein, which is a continuation of U.S. patent
application Ser. No. 10/842,997, filed May 11, 2004, incorporated
by reference herein, and now abandoned. The '997 application is a
divisional of U.S. patent application Ser. No. 10/180,624, filed
Jun. 25 2002, incorporated by reference herein, and issued as U.S.
Pat. No. 7,261,997. U.S. patent application Ser. No. 10/180,624
claims the priority benefit of a provisional application entitled
SPIN BOWL COMPATIBLE POLYAMIC ACIDS/IMIDES AS WET DEVELOPABLE
POLYMER BINDERS FOR BARCS, Ser. No 60/349,569; filed Jan. 17, 2002,
incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is concerned with new polymers and
anti-reflective compositions for use in the manufacture of
microelectronic devices. These compositions include a polyamic acid
and are developable in aqueous photoresist developers.
[0004] 2. Description of the Prior Art
[0005] Integrated circuit manufacturers are consistently seeking to
maximize substrate wafer sizes and minimize device feature
dimensions in order to improve yield, reduce unit case, and
increase on-chip computing power. Device feature sizes on silicon
or other chips are now submicron in size with the advent of
advanced deep ultraviolet (DUV) microlithographic processes.
[0006] However, a frequent problem encountered by photoresists
during the manufacture of semiconductor devices is that activating
radiation is reflected back into the photoresist by the substrate
on which it is supported. Such reflectivity tends to cause blurred
patterns which degrade the resolution of the photoresist.
Degradation of the image in the processed photoresist is
particularly problematic when the substrate is non-planar and/or
highly reflective. One approach to address this problem is the use
of an anti-reflective coating applied to the substrate beneath the
photoresist layer. While anti-reflective coatings are effective at
preventing or minimizing reflection, their use requires an
additional break-through step in the process in order to remove the
coatings. This necessarily results in an increased process
cost.
[0007] One solution to this problem has been the use of wet
developable anti-reflective coatings. These types of coating can be
removed along with the exposed areas of the photoresist material.
That is, after the photoresist layer is exposed to light through a
patterned mask, the exposed areas of the photoresist are wet
developable and are subsequently removed with an aqueous developer
to leave behind the desired trench and hole pattern. Wet
developable anti-reflective coatings are removed during this
developing step, thus eliminating the need for an additional
removal step. Unfortunately, wet developable anti-reflective
coatings have not seen widespread use due to the fact that they
must also exhibit good spin bowl compatibility and superior optical
properties to be useful as an anti-reflective coating. Thus, there
is a need for anti-reflective coating compositions which are
removed by conventional photoresist developers while simultaneously
exhibiting good coating and optical properties.
SUMMARY OF THE INVENTION
[0008] The present invention broadly comprises microlithographic
compositions (and particularly anti-reflective coating
compositions) that are useful in the manufacture of microelectronic
devices.
[0009] In more detail, the compositions comprise a polymer
dispersed or dissolved in a solvent system. In one embodiment, the
preferred polymers are polyamic acids. The polyamic acids
preferably include recurring monomers having the formulas
##STR00002##
where each of
##STR00003##
individually represent an aryl or aliphatic group.
[0010] In this embodiment, the polyamic acids are preferably Formed
by polymerizing a dianhydride with a diamine. Preferred
dianhydrides have the formula a
##STR00004##
where
##STR00005##
represents an aryl or aliphatic group.
[0011] Particularly preferred dianhydrides are:
##STR00006##
[0012] Preferred diamines have the formula
##STR00007##
where
##STR00008##
represents an aryl or aliphatic group.
[0013] Particularly preferred diamines are:
##STR00009##
[0014] In another preferred embodiment, the preferred polymers
include recurring monomers having the formulas
##STR00010##
[0015] In the foregoing formulas, each R is individually selected
from the group consisting of hydrogen, --OH, aliphatics, and
phenyls. Preferred aliphatics are C.sub.1-C.sub.8 branched and
unbranched alkyl groups such as t-butyl and isopropyl groups.
[0016] L is selected from the group consisting of --SO.sub.2-- and
--CR'.sub.2--. When L is --CR'.sub.2--, then each R' is
individually selected from the group consisting of hydrogen,
aliphatics (preferably C.sub.1-C.sub.8 branched and unbranched
alkyls), and phenyls, and --CX.sub.3. In embodiments where R' is
--CX.sub.3, each X is individually selected from the group
consisting of the halogens, with fluorine and chlorine being the
most preferred halogens.
[0017] In yet another embodiment, the polymers are formed by
polymerizing a compound having the formula
##STR00011##
with a compound having the formula
##STR00012##
[0018] In the formulas of this embodiment, each R is individually
selected from the group consisting of --OH, --NH.sub.2, hydrogen,
aliphatics, and phenyls. Again, as with the first embodiment,
preferred aliphatics are C.sub.1-C.sub.8 branched and unbranched
alkyl groups such as t-butyl and isopropyl groups. Furthermore, it
is preferred that at least one R on each ring of (I) be
--NH.sub.2.
[0019] L is preferably selected from the group consisting of
--SO.sub.2-- and --CR'.sub.2--, where each R' is individually
selected from the group consisting of hydrogen, aliphatics
(preferably C.sub.1-C.sub.8 branched and unbranched alkyl groups),
phenyls, and --CX.sub.3. When L is --CX.sub.3, each X is
individually selected from the group consisting of the
halogens.
[0020] Regardless of the embodiment, the compositions are formed by
simply dispersing or dissolving the polymers in a suitable solvent
system, preferably at ambient conditions and for a sufficient
amount of time to form a substantially homogeneous dispersion. The
polymer should be present in the composition at a level of 1-100%
by weight, more preferably from about 20-80% by weight, and more
preferably from about 40-60% by weight, based upon the total weight
of solids in the composition taken as 100% by weight. The weight
average molecular weight of this polymer is preferably from about
2,000-1,000,000 Daltons, more preferably from about 5,000-500,000
Daltons, and even more preferably from about 10,000-100,000
Daltons.
[0021] Preferred solvent systems include a solvent selected from
the group consisting of propylene glycol methyl ether acetate
(PGMEA), propylene glycol methyl ether (PGME), and mixtures
thereof. The solvent system should have a boiling point of from
about 50-250.degree. C., and more preferably from about
150-200.degree. C., and should be utilized at a level of from about
50-99% by weight, and preferably from about 90-98% by weight, based
upon the total weight of the solids in the composition taken as
100% by weight.
[0022] Any other ingredients should be dissolved or dispersed in
the solvent system along with the polymer. One such ingredient is a
crosslinking agent. Preferred crosslinking agents include
aminoplasts (e.g., POWDERLINK.RTM. 1174, Cymel.RTM. products) and
epoxies. The crosslinking agent should be present in the
composition at a level of from about 0-50% by weight, and
preferably from about 10-20% by weight, based upon the total weight
of the solids in the composition talken as 100% by weight. Thus,
the compositions of the invention should crosslink at a temperature
of from about 100-250.degree. C., and more preferably from about
150-200.degree. C.
[0023] It is preferred that the compositions also include a light
attenuating compound or chromophore. The light attenuating compound
should be present in the composition at a level of from about 0-50%
by weight, and preferably from about 15-30% by weight, based upon
the total weight of solids in the composition taken as 100% by
weight. The light attenuating compound should be selected based
upon the wavelength at which the compositions will be processed.
Thus, at wavelengths of 248 nm, preferred light attenuating
compounds include napthalenes and anthracenes, with
3,7-dihydroxy-2-napthoic acid being particularly preferred. At
wavelengths of 365 nm, preferred light attenuating compounds
include diazo dyes and highly conjugated phenolic dyes. At
wavelengths of 193 nm, preferred light attenuating compounds
include compounds containing phenyl rings.
[0024] It will be appreciated that a number of other optional
ingredients can be included in the compositions as well. Typical
optional ingredients include surfactants, catalysts, and adhesion
promoters.
[0025] The method of applying the inventive compositions to a
substrate simply comprises applying a quantity of a composition
hereof to the substrate surface by any known application method
(including spin-coating). The substrate can be any conventional
chip (e.g., silicon wafer) or an ion implant layer.
[0026] After the desired coverage is achieved, the resulting layer
should be heated to induce crosslinking (e.g., to a temperature of
from about 100-250.degree. C.). At a film thickness of about 40 nm
and a wavelength of about 248 nm, the cured layers will have a k
value (i.e., the imaginary component of the complex index of
refraction) of at least about 0.3, and preferably at least about
0.45, and an n value (i.e., the real component of the complex index
of refraction) of at least about 1.0, and preferably at least about
1.8. That is, a cured layer formed from the inventive composition
will absorb at least about 90%, and preferably at least about 99%
of light at a wavelength of about 248 nm. This ability to absorb
light at DUV wavelengths is a particularly useful advantage of the
inventive compositions.
[0027] A photoresist can then be applied to the cured material,
followed by exposing, developing, and etching of the photoresist.
Following the methods of the invention will yield precursor
structures which have the foregoing desirable properties.
[0028] It will further be appreciated that the cured inventive
composition is wet developable. That is, the cured composition can
be removed with conventional aqueous developers such as tetramethyl
ammonium hydroxide or potassium hydroxide developers. At least
about 90%, and preferably at least about 98% of the inventive
coatings will be removed by a base developer such as a tetramethyl
ammonium hydroxide developer (e.g., OPD262, available from Olin
Photodeveloper). This percent solubility in commercially-available
developers is a significant advantage over the prior art as this
shortens the manufacturing process and makes it less costly.
[0029] Finally, in addition to the many advantages described above,
the present composition is spin bowl compatible. This is determined
as described in Example 2, using PGMEA as the solvent and taking
five measurements to determine the average thicknesses. The percent
solubility is calculated as follows:
% solubility = [ ( ave . initial sample thickness - ave . final
sample thickness ) ( initial sample thickness ) ] * 100.
##EQU00001##
The inventive compositions show a percent solubility of at least
about 50%, and more preferably at least about 90%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a Scanning Electron Micrograph (SEM) depicting a
cross-sectional view of a circuit structure showing how a wet
developable anti-reflective layer is removed when the photoresist
is developed;
[0031] FIG. 2 is an SEM of a cross-section of a circuit structure
showing how a conventional thermosetting anti-reflective layer
remains when the photoresist is developed; and
[0032] FIG. 3 an SEM depicting a cross-sectional view of a circuit
structure showing how a wet developable anti-reflective layer
according to the invention is removed when the photoresist is
developed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Examples
[0033] The following examples set forth preferred methods in
accordance with the invention. It is to be understood, however,
that these examples are provided by way of illustration and nothing
therein should be taken as a limitation upon the overall scope of
the invention.
Example 1
[0034] Preparation of Anti-Reflective Coating Composition
1. Polymer Preparation
[0035] A polyamic acid was produced by combining
4,4'-diaminodiphenyl sulfone (4,4'-DPS), 3,3'-dihydroxybenzidene
(HAB), and 4,4'-hexafluoroisopropylidene dipthalic anhydride (6FDA)
(each obtained from KrisKev Corporation) at a molar ratio of
0.46:0.46:1. These ingredients were combined at 60.degree. C. in
diacetone alcohol (obtained from Aldrich). The mixture was stirred
overnight and resulted in a dark brown, viscous liquid having a
solids content of 10% by weight.
2. Anti-Reflective Coating Preparation
[0036] The ingredients of Table 1 were mixed to yield an
anti-reflective coating composition.
TABLE-US-00001 TABLE 1 Formulation I Percentage By Weight.sup.a
Polymer from Part 1 of this Example 1.58% PGMEA.sup.b 48.50%
Diacetone alcohol 48.5% 3,7-dihydroxy-2-napthoic acid 0.95%
Crosslinking Agent.sup.c 0.47% .sup.aBased upon the total weight of
all ingredients in the composition taken as 100% by weight.
.sup.bpropylene glycol monomethyl ether acetate. .sup.cMY720, a
tetra functional epoxy resin available from Araldite; diluted 50%
by weight in diacetone alcohol.
TABLE-US-00002 TABLE 2 Formulation II Percentage By Weight Polymer
from Part 1 of this Example 1.23% PGMEA 48.80% Diacetone alcohol
48.8% 3,7-dihydroxy-2-napthoic acid 0.74% Crosslinking Agent
0.43%
TABLE-US-00003 TABLE 3 Formulation III Percentage By Weight Polymer
from Part 1 of this Example 1.20% PGMEA 48.50% Diacetone alcohol
48.5% 3,7-dihydroxy-2-napthoic acid 0.72% Crosslinking Agent
0.48%
TABLE-US-00004 TABLE 4 Formulation IV Percentage By Weight Polymer
from Part 1 of this Example 2.25% PGMEA 47.75% Diacetone alcohol
47.75% 3,7-dihydroxy-2-napthoic acid 1.35% Crosslinking Agent
0.90%
Example 2
Testing Methods and Results
1. GPC Analysis
[0037] The polymers prepared in Part 1 of this example were
analyzed to determine molecular weight using HPLC with an attached
gel permeation column where n-methyl pyrillidone with
tetrahydrofuran were used as the mobile phase. The polymer prepared
in Part 1 of Example 1 had a molecular weight of 24,908 and a
molecular number of 13,462.
2. Spin Bowl/Solvent Compatibility Test
[0038] Each of the four formulations prepared in Part 2 of Example
1 was subjected to a spin bowl/solvent compatibility test. This
test was carried out by spin-coating the composition onto five 4''
silicon wafers for each sample. After spin-coating, the resulting
layer was allowed to dry for 24 hours at ambient conditions. At
that time, the average initial film thickness on each wafer was
determined using a Stokes ellipsometer. After determining the
thicknesses, each wafer was soaked with a different solvent
(acetone, ethyl lactate, PGMEA, propylene glycol monomethyl ether
(PGME), and 2-heptanone) for 180 seconds, followed by spin drying
at 3500 rpm. The respective average final film thicknesses were
then remeasured using a Stokes ellipsometer. The final thickness
measurements of the samples showed that 100% of the anti-reflective
coating layers had been removed for each solvent.
3. Film Stripping Test
[0039] Each of the anti-reflective coating compositions prepared in
Part 2 of Example 1 were subjected to a film stripping test to
determine the amount of interaction between typical photoresist
solvents and the underlying anti-reflective coating layer. In this
test, a 4'' silicon water was coated with the particular
anti-reflective coating formulation followed by baking at
130.degree. C. for 30 seconds and a second bake at 150.degree. C.
for 60 seconds. The film thickness was then measured using a Stokes
ellipsometer. After measuring the thickness, the wafer was sprayed
with ethyl lactate. The resulting puddle was allowed to stand on
the wager for 10 seconds followed by spin-drying of the wafer at
3500 rpm for 20 seconds. The wafer was then remeasured with a
Stokes ellipsometer to determine the film thickness. The amount of
stripping is the difference between the initial and final film
thickness measurements. The percent stripping is
% stripping = ( amount of stripping initial average film thickness
) .times. 100. ##EQU00002##
Compositions according to the invention will give a percent
stripping of less than about 20%, and preferably less than about
5%. Each of these formulations exhibited no stripping at bake
temperatures of 150-205.degree. C.;
4. V.A.S.E. Measurements
[0040] In this procedure, 4'' silicon wafers were individually
coated with each of the formulations from Part 2 of Example 1. The
respective refractive indices (i.e., n value) and imaginary
refractive indices (i.e., k value) were determined using variable
angle spectrophotometric ellipsometery. Each formulation showed an
n value of 1.1 and a k value of 0.45 at 248 nm.
5. Photolithography
[0041] The formulations of Part 2 of Example 1 were spin-coated
onto respective 8'' silicon substrate at 3500 rpm for 60 seconds,
yielding a film having a thickness of 40 nm. The films were then
baked at 130.degree. C. for 30 seconds, followed by 175.degree. C.
bake for 60 seconds. A commercially available, 500 nm photoresist
(SEPR430, available from Shinetsu) was spin-coated on each
anti-reflective coating layer followed by a soft bake at 90.degree.
C. The photoresist was then patterned with lines and spaces using
an ASML 5500/300 stepper with NANA of 0.63 and annular illumination
with outer sigma of 0.87 and inner sigma of 0.57. After a KrF
excimer laser exposure of 26 mj/cm.sup.2, the photoresist was baked
at 110.degree. C. for 90 seconds. The photoresist and the
anti-reflective coating layer were then developed using a 0.26 N
tetramethyl ammonium hydroxide aqueous developer (available under
the name OPD262). A cross-sectional view of one of the sample
wafers is shown in FIG. 3.
* * * * *